What’s in a field sobriety test?

What's In A Field Sobriety Test?So, you’ve been pulled over and next, you hear these words, “Step out of the car, please.” What happens next? You might be asked to take a field sobriety test.

Sometimes called “roadside sobriety tests”, these field tests are used by police to enforce DUI/DWI laws, and typically include Breathalyzer tests (or they might choose to breathalyze after your field sobriety test.) Usually, the officer will perform a three-part test after a traffic stop if they believe a motorist is drunk, impaired or showing signs of drug use. The test helps the officer assess the motorist for balance, attention and focus (or other factors the officer may be trained in to determine whether or not the driver is under the influence of drugs or alcohol.)

Remember, these officers will record motorist performance on field sobriety tests, which can (or will) be used as evidence in a DUI case. Courts recognize these tests as probable cause to arrest someone suspected of driving under the influence.

Three “standard” parts

The Standardized Field Sobriety Test endorsed by the National Highway Traffic and Safety Administration consists of the horizontal gaze nystagmus, walk-and-turn, and one-leg stand:

  1. Horizontal Gaze Nystagmus: This term refers to the involuntary jerking of the eye that occurs naturally when the eye gazes to the side. But this jerking (or nystagmus) is exaggerated when someone is impaired by alcohol. Officers look for three indicators of impairment in each eye: inability to follow a moving object smoothly; distinct eye jerking when eye is at maximum deviation; and eye-jerking within 45 degrees of center.
  2. Walk and Turn: The purpose of this test, determined to be easily done by most unimpaired people, tests the suspect’s ability to complete tasks with divided attention. This is administered by requiring the suspect to take nine steps, heel-to-toe, along a straight line; turn on one foot; and then return in the same manner in the opposite direction.
  3. One-Leg Stand: Suspects are asked to stand with one foot about six inches off the ground and count for 30 seconds. Swaying while balancing, using arms to balance, hopping or putting the foot down indicate possible impairment.

These three tests (when viewed as a whole) can accurately indicate alcohol impairment in a whopping 91% of cases…in addition, motorists who fail the any or all of the three parts of the standard test are usually given a breathalyzer to determine their blood alcohol concentration (BAC) before an arrest is made.

Non-Standardized Tests 

Other, non-standardized field sobriety tests may include one or more of the following:

  • standing with feet together and tipping the head backwards
  • counting the number of fingers an officer raises
  • reciting the alphabet
  • counting backwards
  • standing and leaning back to look up at the sky while holding arms to the side
  • closing the eyes and touching nose with finger.

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